Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Ras family GTPases (Ras, Rap1, and Rap2) and their downstream mitogen-activated protein kinases (ERK, JNK, and p38MAPK) and PI3K signaling cascades control various physiological processes. In neuronal cells, recent studies have shown that these parallel cascades signal distinct forms of AMPA-sensitive glutamate receptor trafficking during experience-dependent synaptic plasticity and adaptive behavior. Interestingly, both hypo- and hyperactivation of Ras/ Rap signaling impair the capacity of synaptic plasticity, underscoring the importance of a "happy-medium" dynamic regulation of the signaling. Moreover, accumulating reports have linked various genetic defects that either up- or down-regulate Ras/Rap signaling with several mental disorders associated with learning disability (e.g., Alzheimer's disease, Angelman syndrome, autism, cardio-facio-cutaneous syndrome, Coffin-Lowry syndrome, Costello syndrome, Cowden and Bannayan-Riley-Ruvalcaba syndromes, fragile X syndrome, neurofibromatosis type 1, Noonan syndrome, schizophrenia, tuberous sclerosis, and X-linked mental retardation), highlighting the necessity of happy-medium dynamic regulation of Ras/Rap signaling in learning behavior. Thus, the recent advances in understanding of neuronal Ras/Rap signaling provide a useful guide for developing novel treatments for mental diseases.
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PMID:Ras and Rap signaling in synaptic plasticity and mental disorders. 2043 Oct 46

Angelman syndrome (AS) is a neurobehavioral disorder associated with mental retardation, absence of language development, characteristic electroencephalography (EEG) abnormalities and epilepsy, happy disposition, movement or balance disorders, and autistic behaviors. The molecular defects underlying AS are heterogeneous, including large maternal deletions of chromosome 15q11-q13 (70%), paternal uniparental disomy (UPD) of chromosome 15 (5%), imprinting mutations (rare), and mutations in the E6-AP ubiquitin ligase gene UBE3A (15%). Although patients with UBE3A mutations have a wide spectrum of neurological phenotypes, their features are usually milder than AS patients with deletions of 15q11-q13. Using a chromosomal engineering strategy, we generated mutant mice with a 1.6-Mb chromosomal deletion from Ube3a to Gabrb3, which inactivated the Ube3a and Gabrb3 genes and deleted the Atp10a gene. Homozygous deletion mutant mice died in the perinatal period due to a cleft palate resulting from the null mutation in Gabrb3 gene. Mice with a maternal deletion (m-/p+) were viable and did not have any obvious developmental defects. Expression analysis of the maternal and paternal deletion mice confirmed that the Ube3a gene is maternally expressed in brain, and showed that the Atp10a and Gabrb3 genes are biallelically expressed in all brain sub-regions studied. Maternal (m-/p+), but not paternal (m+/p-), deletion mice had increased spontaneous seizure activity and abnormal EEG. Extensive behavioral analyses revealed significant impairment in motor function, learning and memory tasks, and anxiety-related measures assayed in the light-dark box in maternal deletion but not paternal deletion mice. Ultrasonic vocalization (USV) recording in newborns revealed that maternal deletion pups emitted significantly more USVs than wild-type littermates. The increased USV in maternal deletion mice suggests abnormal signaling behavior between mothers and pups that may reflect abnormal communication behaviors in human AS patients. Thus, mutant mice with a maternal deletion from Ube3a to Gabrb3 provide an AS mouse model that is molecularly more similar to the contiguous gene deletion form of AS in humans than mice with Ube3a mutation alone. These mice will be valuable for future comparative studies to mice with maternal deficiency of Ube3a alone.
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PMID:Altered ultrasonic vocalization and impaired learning and memory in Angelman syndrome mouse model with a large maternal deletion from Ube3a to Gabrb3. 2080 28

Christianson syndrome is an X-linked mental retardation syndrome characterized by microcephaly, impaired ocular movement, severe global developmental delay, hypotonia which progresses to spasticity, and early onset seizures of variable types. Gilfillan et al.2008] reported mutations in SLC9A6, the gene encoding the sodium/hydrogen exchanger NHE6, in the family first reported and in three others. They also noted the clinical similarities to Angelman syndrome and found cerebellar atrophy on MRI and elevated glutamate/glutamine in the basal ganglia on MRS. Here we report on nonsense mutations in two additional families. The natural history is detailed in childhood and adult life, the similarities to Angelman syndrome confirmed, and the MRI/MRS findings documented in three affected boys.
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PMID:Natural history of Christianson syndrome. 2094 24

Various rearrangements involve the proximal long arm of chromosome 15, including deletions, duplications, translocations, inversions and supernumerary marker chromosome of an inverted duplication. The large marker 15, that contains the Prader-Willi syndrome (PWS)/Angelman syndrome (AS) chromosome region, is usually associated with an abnormal phenotype of moderate to severe mental retardation, seizures, poor motor coordination, early-onset central hypotonia, autism and autistic-like behavior, schizophrenia and mild dysmorphic features. We report a ten year-old girl with normal intelligence prior to the onset of seizures, who developed severe intractable epilepsy at the age of seven years. Family history was significant for a mother with recurrent episodes of acute psychosis. The patient's and mother's karyotype revealed 47,XX+m. Array comparative genomic hybridization (A-CGH) identified a gain of 13 BAC clones from 15q11.2 through 15q13.1, which was then confirmed by FISH to be part of the marker chromosome. This duplicated region contains the SNRPN/UBE3A locus. This case demonstrates that a duplication of 15q11-13 can present differently in the same family either as intractable epilepsy or as a psychiatric illness and that intelligence can be preserved. We suggest that CGH microarray should be performed in cases with intractable epilepsy or schizophrenia, with or without mental retardation.
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PMID:Familial partial trisomy 15q11-13 presenting as intractable epilepsy in the child and schizophrenia in the mother. 2114 72

The study of distinctive and consistent behaviors in the most common genetic syndromes with intellectual disability is useful to explain abnormalities or associated psychiatric disorders. The behavioral phenotypes revealed outcomes totally or partially specific for each syndrome. The aim of our study was to compare similarities and differences in the adaptive profiles of the five most frequent genetic syndromes, i.e. Down syndrome, Williams syndrome, Angelman syndrome, Prader-Willi syndrome, and Fragile-X syndrome (fully mutated), taking into account the relation with chronological age and the overall IQ level. The research was carried out using the Vineland Adaptive Behavior Scale (beside the Wechsler Intelligence scales to obtain IQ) with a sample of 181 persons (107 males and 74 females) showing genetic syndromes and mental retardation. Syndrome-based groups were matched for chronological age and mental age (excluding the Angelman group, presenting with severe mental retardation). Similarities and differences in the adaptive profiles are described, relating them to IQs and maladaptive behaviors. The results might be useful in obtaining a global index of adjustment for the assessment of intellectual disability level as well as for educational guidance and rehabilitative plans.
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PMID:Behavioral phenotypes of genetic syndromes with intellectual disability: comparison of adaptive profiles. 2150 90

Recent data suggest that the levels of many synaptic proteins may be tightly controlled by the opposing processes of new translation and protein turnover in neurons. Alterations in this balance or in the levels of such dosage-sensitive proteins that result in altered stoichiometry of protein complexes at developing and remodeling synapses may underlie several human cognitive diseases including Fragile X Syndrome, autism spectrum disorders, Angelman syndrome and non-syndromic mental retardation. While a significant amount is known about the transduction of membrane signals to the translational apparatus through kinase cascades acting on general translation factors, much less is understood about how such signals may influence the activity of mRNA-specific regulators, their mechanisms of action and the specific sets of mRNAs they regulate. New approaches to the unbiased in vivo identification of maps of binding sites for these proteins on mRNA is expected to greatly increase our understanding of this crucial level of regulation in neuronal development and function.
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PMID:Defects in translational regulation contributing to human cognitive and behavioral disease. 2176 93

SLC9A6 mutations have been reported in families in whom X-linked mental retardation (XMR) mimics Angelman syndrome (AS). However, the relative importance of SLC9A6 mutations in patients with an AS-like phenotype or XMR has not been fully investigated. Here, the involvement of SLC9A6 mutations in 22 males initially suspected to have AS but found on genetic testing not to have AS (AS-like cohort), and 104 male patients with XMR (XMR cohort), was investigated. A novel SLC9A6 mutation (c.441delG, p.S147fs) was identified in one patient in the AS-like cohort, but no mutation was identified in XMR cohort, suggesting mutations in SLC9A6 are not a major cause of the AS-like phenotype or XMR. The patient with the SLC9A6 mutation showed the typical AS phenotype, further demonstrating the similarity between patients with AS and those with SLC9A6 mutations. To clarify the effect of the SLC9A6 mutation, we performed RT-PCR and Western blot analysis on lymphoblastoid cells from the patient. Expression of the mutated transcript was significantly reduced, but was restored by cycloheximide treatment, indicating the presence of nonsense mediated mRNA decay. Western blot analysis demonstrated absence of the normal NHE6 protein encoded for by SLC9A6. Taken together, these findings indicate a loss-of-function mutation in SLC9A6 caused the phenotype in our patient.
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PMID:A loss-of-function mutation in the SLC9A6 gene causes X-linked mental retardation resembling Angelman syndrome. 2181

Methyl-CpG binding protein 2 gene (MECP2) testing is indicated for patients with numerous clinical presentations, including Rett syndrome (classic and atypical), unexplained neonatal encephalopathy, Angelman syndrome, nonspecific mental retardation, autism (females), and an X-linked family history of developmental delay. Because of this complexity, a gender-specific approach for comprehensive MECP2 gene testing is described. Briefly, sequencing of exons 1 to 4 of MECP2 is recommended for patients with a Rett syndrome phenotype, unexplained neonatal encephalopathy, an Angelman syndrome phenotype (with negative 15q11-13 analysis), nonspecific mental retardation, or autism (females). Additional testing for large-scale MECP2 deletions is recommended for patients with Rett syndrome or Angelman syndrome phenotypes (with negative 15q11-13 analysis) following negative sequencing. Alternatively, testing for large-scale MECP2 duplications is recommended for males presenting with mental retardation, an X-linked family history of developmental delay, and a significant proportion of previously described clinical features (particularly a history of recurrent respiratory infections).
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PMID:Algorithmic approach for methyl-CpG binding protein 2 (MECP2) gene testing in patients with neurodevelopmental disabilities. 2212 27

Mutations in the X-linked gene encoding Methyl-CpG-binding protein 2 (MECP2) have been associated with neurodevelopmental and neuropsychiatric disorders including Rett Syndrome, X-linked mental retardation syndrome, severe neonatal encephalopathy, and Angelman syndrome. Although alterations in the performance of MeCP2-deficient mice in specific behavioral tasks have been documented, it remains unclear whether or not MeCP2 dysfunction affects patterns of periodic behavioral and electroencephalographic (EEG) activity. The aim of the current study was therefore to determine whether a deficiency in MeCP2 is sufficient to alter the normal daily rhythmic patterns of core body temperature, gross motor activity and cortical delta power. To address this, we monitored individual wild-type and MeCP2-deficient mice in their home cage environment via telemetric recording over 24 hour cycles. Our results show that the normal daily rhythmic behavioral patterning of cortical delta wave activity, core body temperature and mobility are disrupted in one-year old female MeCP2-deficient mice. Moreover, female MeCP2-deficient mice display diminished overall motor activity, lower average core body temperature, and significantly greater body temperature fluctuation than wild-type mice in their home-cage environment. Finally, we show that the epileptiform discharge activity in female MeCP2-deficient mice is more predominant during times of behavioral activity compared to inactivity. Collectively, these results indicate that MeCP2 deficiency is sufficient to disrupt the normal patterning of daily biological rhythmic activities.
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PMID:Daily rhythmic behaviors and thermoregulatory patterns are disrupted in adult female MeCP2-deficient mice. 2252 89

Angelman syndrome is a neurodevelopmental disorder characterized by global developmental delay, mental retardation, seizures, microcephaly, and severe speech delay. It may be caused by deletion of chromosome region 15q11.2 of the maternally inherited chromosome, mutations in the UBE3A gene, uniparental disomy, or imprinting defects. Most patients with this diagnosis have a severe phenotype, and a few have a mild form of the disease. We report a patient with a novel mutation in the UBE3A gene that consists of a deletion of the termination codon (c.2556-*+6del GTAAAACAAA) and results in an elongated protein E3 ubiquitin-protein ligase. Our patient has a mild phenotype compared with other patients in general and specifically to patients with UBE3A mutations. He has mild developmental delay, moderate speech delay, and no seizures. Recognition of this genotype-phenotype correlation will allow better genetic counseling to other patients with similar stop codon mutations.
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PMID:Angelman syndrome due to a termination codon mutation of the UBE3A gene. 2256 13


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